The compound 2-methyl-2-phenyl-4-hexanone having the structure: ##STR5## is well known as having an outstanding rose fragrance. Thus, the United Kingdom Pat. No. 1,105,455 discloses the use of this material in perfumery and further indicates that a process can be use to prepare this material by reacting an acyl chloride with the Grignard reagent having the structure: ##STR6## Indeed, United Kingdom patent specification No. 1,105,455 specifically discloses the reaction: ##STR7## and indicates that such reaction preferably takes place in the precense of cadium chloride. United Kingdom patent specification No. 1,105,455 however, does not actually exemplify such a reaction and further does not alude to the unexpected, unobvious and advantageous increase in yield by carrying out the alternative reaction of our invention using propianic anhydride and the Grignard reagent having the structure: ##STR8## and further does not indicate the advantage from a yield standpoint of first reacting the Grignard reagent having the structure: ##STR9## with manganese chloride to form the novel intermediate having the structure: ##STR10## and then reacting the said intermediate having the structure: ##STR11## with propionyl chloride having the structure: ##STR12##
Although the generic reaction of an acyl anhydride with an alkyl magnesium halide to form a ketone is well known in organic chemistry, that is the reaction: ##STR13## as it is indicated by Newman & Smith at J. Org. Chem. 13, 592-8 (1948) wherein R is methyl and R' may be secondary butyl, tertiary butyl, n-butyl or phenyl, the reaction of a sterically hindered Grignard reagent with an acyl anhydride or the unexpected, advantageous improvement in yield by first forming the mangenese organometallic intermediate from the Grignard reagent and then reacting it with an acyl chloride is not so taught in the prior art.